共查询到20条相似文献,搜索用时 15 毫秒
1.
《Inorganica chimica acta》1988,146(1):65-73
The oxovanadium(IV), acetatomanganese(III), chloroiron(III), nickel(II), copper(II), zinc(II) and palladium(II) of 3,3′-(1,2-phenylenediimino)diacrolein were prepared and investigated by means of mass, electronic, vibrational, NMR and ESR spectroscopy as well as magnetic susceptibility measurements. The acetatomanganese(III) and chloroiron(III) complexes were confirmed to be of high spin type. The absorption bands appearing in the energy range greater than 23 000 cm−1 were attributed to π→π* transitions within a ligand molecule and charge- transfer transitions from metal to ligand. The metal complexes assume the square-planar configuration type since the ligand-field bands were detected in the 12 700–18 500 cm−1 region. Strong bands appearing at 1601 and 1627 cm−1 were assigned to the CC and CO stretching vibrational modes, respectively, and were shifted to lower frequency upon metal-coordination. A VO stretching band was observed at 982 cm−1 for the oxovanadium(IV) complex and a CO stretching band was observed at 1547 cm−1 for the acetatomanganese(III) complex. Upon complex formation the amine proton signal is found to vanish and the aldehydic methine proton signal in the lowest field is shifted upfield for the nickel(II), zinc(II) and palladium(II) complexes. 13C NMR spectra support the coordination structure of the complexes which is revealed by 1H NMR spectra. As judged by the spin Hamiltonian parameters, the oxovanadium(IV) complex is of a square- planar type with an unpaired electron in the dxy orbital and the copper(II) complex assumes a distorted square-planar coordination due to the presence of five- and six-membered chelate rings with an unpaired electron in the dx2−y2 orbital. 相似文献
2.
《Inorganica chimica acta》1988,151(2):125-128
The interactions of dichloro-bis(η5-cyclopentadienyl)titanium(IV) (titanocene dichloride, Cp2TiCl2) with nucleosides have been studied in methanolic solutions. Complexes of the general formula [Cp2Ti(Nucl)MeOH]Cl2 were isolated. The nucleoside complexes with one N(1)H ionizable imino proton (i.e. inosine and guanosine) undergo ionization in alkaline solution and complexes of the formula [Cp2Ti(NuclH+)] Cl were isolated. All complexes have been characterized by elemental analyses and various spectroscopic techniques. In the first series of complexes, [Cp2Ti(Nucl)MeOH]Cl2, the nucleosides act as monodentate ligands with an intramolecular hydrogen bond between the coordinated methanol and the C6O group, while in the second, [Cp2Ti(NuclH+)] Cl, they coordinate through both their N7 and O6 atoms. 相似文献
3.
《Chemical Speciation and Bioavailability》2013,25(3):137-148
AbstractThe formation of complex species in the dimethyltin(IV) and trimethyltin(IV)-carboxymethyl-L-cysteinate (carbocysteinate) systems in NaClaq, at different ionic strengths, and in a multicomponent Na+, K+, Ca2+ ,Mg2+, Cl? and SO42-? medium representative of the seawater major composition, is discussed. Experimental results give evidence for the formation of the following species (L = carbocysteinate): [(CH3)2Sn(L)]0, [(CH3)2Sn(HL)]+, [(CH3)2Sn(OH)(L)]?, [(CH3)2Sn(OH)2(L)]2? in the DMT–CCYS system, and [(CH3)3Sn(HL)]0, [(CH3)3Sn(L)]? and [(CH3)3Sn(OH)(L)]2? in the TMT-CCYS system. The ionic strength dependence of formation constants was taken into account by an extended Debye Hückel type equation and by the SIT (Specific ion Interaction Theory). Measurements were carried out also on the dimethyltin(IV)-glutamate and trimethyltin(IV)-glutamate systems in NaClaq, owing the strict similarity of glutamate and carbocysteinate. Results obtained show the formation of complex species having the same stoichiometry as those formed in the DMT- and TMT-carbocysteinate systems, with very similar stability, confirming that carbocysteinate behaves as a dicarboxylic amino acid without involving the sulfur-bridge potential binding site in metal coordination. 相似文献
4.
《Inorganica chimica acta》1986,122(1):37-44
5.
L.A. Tomachynski I.N. Tretyakova V.Ya. Chernii S.V. Volkov M. Kowalska J. Legendziewicz Y.S. Gerasymchuk St. Radzki 《Inorganica chimica acta》2008,361(9-10):2569-2581
The series of new zirconium(IV) and hafnium(IV) phthalocyanines with various β-dicarbonyl ligands were prepared via direct interaction between di(chloro)zirconium(IV) or hafnium(IV) phthalocyanines and free β-diketones and also with 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one. The structure of the obtained bis(β-dicarbonilato) zirconium(IV) and hafnium(IV) phthalocyanines was studied by two dimension 1H NMR spectroscopy (COSY, NOESY, ROESY). Absorption and fluorescence spectroscopic studies have been investigated in various solvents. Analyzed compounds of concentration range below 10?5 mol/dm3 do not aggregate in the organic solvents. Fluorescence quantum yields (ΦF) and natural life times (τ) of zirconium phthalocyanine complexes have been calculated in toluene, DMSO and THF. 相似文献
6.
Rengaswami Chandrasekaran Andrea Giacometti Struther Arnott 《Journal of biomolecular structure & dynamics》2013,31(6):1011-1022
Abstract The molecular structure of poly (dT)·poly (dA)·poly (dT) has been determined and refined using the continuous x-ray intensity data on layer lines in the diffraction pattern obtained from an oriented fiber of the DNA. The final R-value for the preferred structure is 0.29 significantly lower than that for plausible alternatives. The molecule forms a 12-fold right- handed triple-helix of pitch 38.4 Å and each base triplet is stabilized by a set of four Crick-Watson-Hoogsteen hydrogen bonds. The deoxyribose rings in all the three strands have C2′-endo conformations. The grooveless cylindrical shape of the triple-helix is consistent with the lack of lateral organization in the fiber. 相似文献
7.
Antisense strategies that target DNA·RNA hybrid structures offer potential for the development of new therapeutic drugs. The α-sarcin loop region of the 16S rRNA domain has been shown to be a high value target for such strategies. Herein, aminoglycoside interaction with three RNA·DNA α-sarcin targeted duplexes (rR·dY, rR·S-dY, and rR·2'OMe-rY) have been investigated to determine the overall effect of aminoglycoside interaction on the stability, affinity, and conformation of these hybrid duplexes. To this end, UV thermal denaturation, circular dichroism spectroscopy, fluorescence intercalator displacement, and ITC as well as DSC calorimetry experiments were carried out. The results suggest the following. (1) Of all the aminoglycosides studied, neomycin confers the highest thermal stability on all three hybrid duplexes studied. (2) There is no appreciable difference in aminoglycoside-induced thermal stability between the unmodified rR·dY and phophorothioate modified rR·S-dY duplexes. (3) The rR·2'OMe-rY duplexes thermal stability is slightly less than the other two hybrids. (4) In all three duplexes, aminoglycoside-induced thermal stability decreased as the number of amino groups decreased. (5) CD scans revealed similar spectra for the rR·dY and rR·S-dY duplexes as well as a more pronounced A-form signal for the rR·2'OMe-rY duplex. (6) FID assays paralleled the CD results, yielding similar affinity values between the rR·dY and rR·S-dY duplexes and higher affinities with the rR·2'OMe-rY duplex. (7) The overall affinity trend between aminoglycosides and the three duplexes was determined to be neomycin > paromomycin > neamine > ribostamycin. (8) ITC K(a) values revealed similar binding constants for the rR·dY and rR·S-dY duplexes with rR·dY having a K(1) of (1.03 ± 0.58) × 10(7) M(-1) and K(2) of (1.13 ± 0.07) × 10(5) M(-1) while rR·S-dY produced a K(1) of (1.17 ± 0.54) × 10(7) M(-1) and K(2) of (1.27 ± 0.69) × 10(5) M(-1). (8) The rR·2'OMe-rY produced a slightly higher binding constant values with a K(1) of (1.25 ± 0.24) × 10(7) M(-1) and K(2) of (3.62 ± 0.18) × 10(5) M(-1). (9) The ΔT(m)-derived K(Tm) of 3.81 × 10(7) M(-1) for rR·S-dY was in relative agreement with the corresponding K(1) of 1.17 × 10(7) M(-1) derived constant from the fitted ITC. These results illustrate that the increased DNA·RNA hybrid duplex stability in the presence of aminoglycosides can help extend the roles of aminoglycosides in designing modified ODNs for targeting RNA. 相似文献
8.
9.
《Inorganica chimica acta》1986,122(1):111-118
The title complex, prepared in 1 M NaOH, was crystallized from hot N,N-dimethylformamide/ ethanol solutions to give Na12[Ce(C6H2O2(SO3)2)4]· 9H2O·6DMF. The purple—brown crystals were examined by X-ray diffraction while inside quartz capillaries filled with DMF, (λmax 425 nm, ϵ 3664; λsh 520 nm, ϵ 2240) and belong to space group Pbca, Z=8 with a=21.846(4), b=17.348(2), c=43.103- (6) Å, V=16.335(7) Å3, Dc=1.693 gcmt−3, Do=1.725 g cmt−3. Diffractometer data were collected using Mo Kα radiation to 2θ=43o. For 7331 independent data with Fo2>3σ(Fo2) full matrix least squares refinement converged to unweighted and weighted R factors of 0.072 and 0.110, respectively, with a mixture of anisotropic and isotropic thermal parameters. The disordered DMF atom parameters were not refined. The structure consists of discrete monomeric Ce(C6H2S2O8)412− units with 12 Na+ counter cations and 10 H2O molecules (two with half occupancy), and 6 DMF molecules of solvation filling up spaces between cations and anions. Cerium(IV) is in a general position with a coordination polyhedron close to the trigonal-faced dodecahedron, D2d, with the angles between the two BAAB trapezoids of 2.3o and 3.7o. The average CeO(A) distance, 2.363(9) Å is longer than the average CeO(B) distance, 2.326(15)Å, with the reverse being true for one of the four tironato ligands. The average ring OCeO angle is 67.9(1)o. The cerium (IV) complex is found by cyclic voltammetry to undergo a quasi-reversible one-electron reduction (in strongly basic solution with excess tiron) with Ef=−497 mV vs. SCE, hence the ratio of the formation constants for tetrakis(tironato)cerate(IV) to that for tetrakis(tironato)cerate(III), KIV/KIII, is 1033. Characterization of other tiron salts is reported. 相似文献
10.
《Inorganica chimica acta》1986,114(2):141-144
The preparations and properties of tris(dipivaloylmethanato)technetium(III), tris(trifluoroacetylacetonato)technetium(III), and tris(hexafluoroacetonato)technetium(III) are described. The oxidation of the dipivaloyl derivative to tris(dipivaloyl)technetium(IV) hexafluorophosphate was shown to take place readily. Voltammetric studies and magnetic resonance results on the new complexes are reported. The large shifts observed for the complexes seem to be due to a contact interaction. 相似文献
11.
12.
The chief motive behind this research is the interest provoked by the presence of metal ions as necessary stabilizers of the negative charges of phosphate groups in nucleic acids. The effect that the presence of different metal ions produces on the band principally assigned to the nu(s) PO(3)(2-) mode has been studied using FT-IR and FT-Raman spectroscopy. The results obtained reveal the diagnostic capacity of these techniques in determining the type of metal ion interaction with respect to the mononucleotides that form DNA and RNA, providing a tool for improving the knowledge of the stabilizing or destabilizing effects of these ions on such macromolecules. The metal complexes of the ribonucleotides 5'-CMP and 5'-GMP with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III) were obtained in this study. After studying and analyzing the IR and Raman spectra of all these complexes and comparing them with the spectra of the corresponding disodium salts, it was verified that, independently of the type of nucleotide involved, the presence of the metal in the vicinity of the phosphate group produces an alteration in the aforementioned nu(s) PO(3)(2-) band. This effect is related to the type of interaction that the phosphate group has with the metal. Three components are observed: (1) one near 983-975 cm(-1) (detectable in IR and Raman), associated with phosphate groups in an electrostatic type of interaction with the metal ion, separated by two or more water molecules; (2) another near 989-985 cm(-1) (only in IR), associated with phosphate groups in indirect interaction through the water molecules of the coordination sphere of the metal ions; and (3) the IR and Raman bands near 1014-1001 cm(-1), which represent phosphate groups directly bonded to the metal ion. These results are supported by the behavior of 5'-CMP in aqueous solution in the presence of Mg(II) ions. 相似文献
13.
A new ligand N-Nicotinoyl-N-o-hydroxythiobenzhydrazide (H2Notbh) forms complexes [Mn(Notbh)(H2O)], [M(Notbh)] [M=Ni(II) Cu(II) and Zn(II)] which were characterized by various physico-chemical techniques. All the metal complexes were observed to inhibit the growth of tumor in vitro, whereas, ligand did not. In vivo administration of these complexes resulted in prolongation of survival of tumor bearing mice. Tumor bearing mice administered with metal complexes showed reversal of tumor growth associated induction of apoptosis in lymphocytes. The paper discusses the possible mechanisms and therapeutic implication of the H2Notbh and its metal complexes in tumor regression and tumor growth associated immunosuppression. 相似文献
14.
Larisa A. Tomachynski Victor Ya. Chernii Alexander N. Chernega Sergey V. Volkov 《Inorganica chimica acta》2007,360(5):1493-1501
The synthesis of new zirconium and hafnium mixed ligand phthalocyanine complexes PcM(β-ketoester)2, where M-Zr (IV), Hf (IV); Pc - the dianion of phthalocyanine, and β-ketoester - the out planed ligand, is reported. The obtained complexes are characterized by 1H NMR, IR, UV-Vis spectroscopy and cyclic voltammetry. 1H NMR and elemental analysis confirm the substitution of two Cl atoms for two β-ketoester fragments to the central atom of the macrocycle. The data of 1H NMR, UV-Vis spectroscopy have allowed us to conclude that two β-ketoester ligands are in the cis geometry to the phthalocyanine plane. X-ray crystallography for bis(isopropyl 3-oxobutanoato)hafnium(IV)phthalocyanine confirms this conclusion. The central macrocycle of the phthalocyanine ligand is not exactly planar (deviations from the least-square plane exceed 0.15 Å) and has the conformation of an essentially flattened crown. The Hf(1) atom is 1.349(3) above this least-square plane. Cyclic voltammetry investigation shows that the introduction of two β-ketoester ligands to the central atom of phthalocyanine complex leads to both chemical and electrochemical stabilization of the whole Pc system. 相似文献
15.
Tapan K. Paine Miquel Costas József Kaizer Lawrence Que Jr 《Journal of biological inorganic chemistry》2006,11(3):272-276
The oxoiron(IV) complexes of two 6-substituted tris(2-pyridylmethyl)amine ligand derivatives have been generated and characterized
with respect to their spectroscopic and reactivity properties. The introduction of an α-substituent maintains the low-spin
nature of the oxoiron(IV) unit but weakens the ligand field, as evidenced by red shifts in its characteristic near-IR chromophore.
While its hydrogen-atom abstraction ability is only slightly affected, the oxo-transfer reactivity of the oxoiron(IV) center
is significantly enhanced relative to that of the parent complex. These results demonstrate that the ligand environment plays
a key role in modulating the reactivity of this important biological oxidant.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
An erratum to this article can be found at 相似文献
16.
17.
《Inorganica chimica acta》1988,145(2):285-288
The stability constants and the heats of formation of vanadyl(IV)—acetate, —glycolate, and —glycine complexes have been determined in aqueous solution by means of potentiometric and calorimetric measurements. In the pH range where the protolitic equilibria of VO2+ is certainly negligible the acetate forms two mononuclear complexes, the glycolate three whereas the glycine reacts in its zwitterionic form. The stabilities of the glycolate complexes are considerably higher than the acetate ones, in spite of its lower basicity, indicating that the complex formation involves the coordination of the hydroxyl group to the metal ion. The enthalpy changes are positive except for the glycolate where a small negative value is found. For all systems the entropy changes are positive and therefore favourable to the complex formation. 相似文献
18.
《Inorganica chimica acta》1986,123(2):87-90
Derivatives of Co(II), Ni(II), Cu(II) and Zn(II) with 3′AMP and 2′AMP were synthesized and characterized by IR UV-Vis and fluorescence spectroscopy. There seems to be bonding of the metal ion to the base in all cases. The activation test, using the complexes as allosteric labels, was carried out with rabbit muscle glycogen phosphorylase b, but the enzyme was not activated, confirming that the phosphate group must necessarily be bonded to position 5′ of the ribose in order to activate this enzyme. 相似文献
19.
《Inorganica chimica acta》1987,129(2):273-276
The pentadentate ligand 2,6-diacetylpyridinedisemicarbazone, DAPSC, reacts with Th(NO3)4 in ethanolwater mixture and a di-μ-hydroxo Th(IV) dimer is formed. The compound [Th2(OH)2(DAPSC)2(NO3)2(H2O)2](NO3)4·4H2O (I) is monoclinic, space group P21/n with a = 10.705(1), b = 19.008(2), c = 11.782(1) Å, β = 107.82(2)°, V = 2282(1) Å3 and Z = 2. Detailed X-ray structural analysis showed that each thorium atom in the complex is coordinated to one pentadentate DAPSC ligand, which is subjected to a considerable distortion, one bidentate nitrate group, one water ligand and two bridging hydroxo groups. The coordination number is ten and the best presentation of the polyhedron is that of a distorted bicapped square antiprism. The ThTh separation is 4.0181(6) Å and the average ThO(H) bridge is 2.366 Å. The structure was refined using 3185 reflections to an R value of 5.0%. 相似文献
20.